Gas wiping nozzle, gas injection device, and method for manufacturing hot-dip metal coated steel sheet

Abstract

Provided are a gas wiping nozzle, a gas injection device, and a method for manufacturing a hot-dip metal coated steel sheet capable of suppressing damage to a ceramic member.SOLUTION: A gas wiping nozzle (31) is a gas wiping nozzle that adjusts a film thickness of molten metal adhering to a surface of a steel strip by blowing gas to the steel strip pulled upward from a molten metal plating bath, and includes a ceramic nozzle portion (33) having a supply port (32) to which gas is supplied and a jet port (35) for blowing the supplied gas, in which a film-shaped heat-resistant material (60) is provided on at least a part of a surface of the nozzle portion on a side close to the supply port.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a gas wiping nozzle, a gas injection device, and a method for manufacturing a hot-dip metal coated steel sheet.The present disclosure particularly relates to a gas wiping nozzle for spraying a wiping gas onto a metal strip, a gas injection device, and a method for manufacturing a hot-dip metal coated steel sheet. [Background technology]

[0002] Hot-dip galvanized metal strips, which are a type of hot-dip metal-coated metal strip, are widely used in fields such as building materials, automobiles, and home appliances. Hot-dip galvanized metal strips are required to have excellent appearance. The appearance of hot-dip galvanized metal strips after painting is strongly affected by surface defects such as uneven coating thickness, scratches, and foreign matter adhesion. Therefore, hot-dip galvanized metal strips are required to be free of surface defects.

[0003] Hot-dip metal-plated metal strips are generally produced in a continuous hot-dip metal plating line, in which a metal strip is continuously introduced into molten metal stored in a plating tank, a wiping gas is sprayed onto the metal strip from a gas wiping nozzle to adjust the plating thickness, and the metal strip is cooled and then subjected to post-processing.

[0004] A pair of gas wiping nozzles are arranged above a plating tank, for example, with the metal strip sandwiched between them. The molten metal scattered by the wiping gas is called splash. If the splash adheres to the inside of the slit of the gas wiping nozzle, the flow path of the wiping gas is blocked. This prevents the wiping gas from being sprayed uniformly from the gas wiping nozzle, resulting in surface defects such as uneven film thickness.

[0005] Patent Document 1 discloses spraying ceramics that do not undergo alloying reaction with molten metal onto the tip of a gas wiping nozzle to suppress adhesion of splashes into the slit. Patent Document 2, based on a similar concept, discloses bonding ceramics to the tip of the gas wiping nozzle. Patent Document 3 discloses a gas wiping nozzle whose nozzle tip is made of ceramics. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 62-203260 [Patent Document 2] Japanese Utility Model Application Publication No. 62-203261 [Patent Document 3] Japanese Utility Model Application Publication No. 01-147252 Summary of the Invention [Problem to be solved by the invention]

[0007] The gas wiping nozzles described in Patent Documents 1 to 3 damage ceramic members during wiping. Typically, the wiping gas is pressurized by a compressor, which increases the gas temperature to 100 to 150°C at the nozzle outlet. In such an environment, the difference in linear expansion coefficients between the metal and ceramic members causes a difference in the amount of thermal expansion at the boundary between the metal and ceramic members. Thermal stress at the interface between the metal and ceramic members causes damage to the ceramic member. The damage causes unevenness in the wiping gas, resulting in new defects on the plating surface.

[0008] In view of the above problems, the present disclosure aims to provide a gas wiping nozzle, a gas injection device, and a method for manufacturing a hot-dip metal-plated steel sheet that can suppress damage to ceramic members. [Means for solving the problem]

[0009] (1) A gas wiping nozzle according to an embodiment of the present disclosure includes: A gas wiping nozzle that sprays gas onto a steel strip pulled up from a molten metal plating bath to adjust the film thickness of molten metal adhering to the surface of the steel strip, a ceramic nozzle portion having a supply port through which the gas is supplied and an ejection port through which the supplied gas is ejected, A gas wiping nozzle, wherein a film-like heat-resistant material is provided on at least a portion of the surface of the nozzle portion on the side closer to the supply port.

[0010] (2) As one embodiment of the present disclosure, in (1), The temperature of the gas to be sprayed is in the range of 100°C to 150°C.

[0011] (3) As an embodiment of the present disclosure, in (1) or (2), The melting point of the molten metal is defined as TM (°C), and the temperature of the gas being sprayed is TM-150 (°C) or higher.

[0012] (4) As an embodiment of the present disclosure, in any one of (1) to (3), The nozzle portion and the metal flange are mechanically connected via the heat-resistant material.

[0013] (5) As an embodiment of the present disclosure, in (4), the nozzle portion and the flow rectifying plate are mechanically connected via the heat-resistant material, The flange is mechanically connected to a side of the rectifying plate that is different from the side to which the nozzle portion is connected.

[0014] (6) A gas injection device according to an embodiment of the present disclosure includes: The gas wiping nozzle is any one of (1) to (5).

[0015] (7) A method for producing a hot-dip metal-plated steel sheet according to an embodiment of the present disclosure includes: (6) A hot-dip metal coated steel sheet is manufactured using the gas injection device. [Effects of the Invention]

[0016] According to the present disclosure, it is possible to provide a gas wiping nozzle, a gas injection device, and a method for manufacturing a hot-dip metal-plated steel sheet that can suppress damage to ceramic members. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the general configuration of a manufacturing facility for hot-dip metal-plated steel sheets. [Figure 2] FIG. 2 is a perspective view showing a schematic configuration of a gas wiping nozzle used in the manufacturing facility for hot-dip metal-plated steel sheets shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the metal-ceramic interface of a gas wiping nozzle of a conventional configuration. [Figure 4] FIG. 4 is a cross-sectional view of a metal-ceramic interface of a gas wiping nozzle according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] A gas wiping nozzle 31 (see FIG. 1), a gas injection device 30 (see FIG. 1), and a method for manufacturing a hot-dip metal-plated steel sheet according to one embodiment of the present disclosure will be described below with reference to the drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals. In the following description of the embodiment, the description of identical or corresponding parts will be omitted or simplified as appropriate.

[0019] <Equipment configuration> FIG. 1 shows a manufacturing facility 100 (continuous hot-dip metal coating facility) for hot-dip metal coated steel sheets that is equipped with a gas injection device 30 according to this embodiment.

[0020] As shown in FIG. 1, the manufacturing equipment 100 for hot-dip metal-plated steel sheets is equipment for manufacturing hot-dip metal-plated steel sheets by immersing a steel strip S (an example of a metal strip) in molten metal M, thereby continuously depositing the molten metal M on the front and back surfaces of the steel strip S.

[0021] Although the metal strip is not particularly limited, the present embodiment will be described as a steel strip S. As the steel strip S, for example, one that has been annealed in a continuous annealing furnace in a reducing atmosphere is used.

[0022] The manufacturing equipment 100 for hot-dip metal-plated steel sheets includes a coating tank 10 in which molten metal M is stored, a snout 20 that supplies a steel strip S to the coating tank 10, and a gas injection device 30 that adjusts the amount of molten metal M adhering to the steel strip S. The manufacturing equipment 100 for hot-dip metal-plated steel sheets executes a manufacturing method for hot-dip metal-plated steel sheets. The manufacturing method for hot-dip metal-plated steel sheets includes, as one of its steps, a step of adjusting the film thickness of the molten metal M adhering to the surface of the steel strip S by the gas injection device 30. Here, known techniques may be used for the other steps of manufacturing the hot-dip metal-plated steel sheets.

[0023] The snout 20 is a hollow cylindrical member. The snout 20 is provided so as to cover the periphery of the steel strip S. The snout 20 is formed, for example, so that the cross section perpendicular to its axial direction is rectangular. The upper end side of the snout 20 is connected to, for example, the outlet side of a continuous annealing furnace, and the lower end side is connected to the inside of the coating tank 10.

[0024] The plating tank 10 is formed in the shape of a tank with a bottom so that it can store molten metal M. The plating tank 10 is formed with an open top. The lower end side of the snout 20 is inserted so as to be immersed in the molten metal M stored in the plating tank 10. A sink roll 40 and a support roll 50 are arranged in the plating tank 10. The steel strip S is stretched over the sink roll 40, passes through the support roll 50, and is discharged to the outside from the opening of the plating tank 10. The sink roll 40 applies an appropriate tension to the steel strip S and functions as a transport section that transports the steel strip S toward the plating tank 10 and the gas injection device 30.

[0025] The molten metal M is not particularly limited, and may be, for example, zinc, aluminum, or tin. When zinc is used as the molten metal M, the steel strip S is produced as a hot-dip galvanized metal strip. The hot-dip galvanized metal strip may be, for example, a galvanized steel sheet (GI) that is not subjected to an alloying treatment after the hot-dip galvanizing treatment, or a galvanized steel sheet (GA) that is subjected to an alloying treatment.

[0026] The gas injection device 30 has a gas wiping nozzle 31 that sprays gas (wiping gas) onto the steel strip S pulled upward from the molten metal coating bath (coating tank 10) to adjust the film thickness of the molten metal M adhering to the surface of the steel strip S. In this embodiment, a pair of gas wiping nozzles 31 are arranged so as to sandwich the front and back surfaces of the steel strip S. The wiping gas is not particularly limited, but for example, gas pressurized by a compressor or a gas mixed with exhaust gas from a combustor and air can be used.

[0027] The temperature T (°C) of the sprayed gas, ie, the wiping gas immediately after being discharged from the tip of the wiping nozzle, is increased by a compressor to a range of 100°C to 150°C, for example.

[0028] When manufacturing thick-plated products, the occurrence of melt wrinkles can be suppressed by increasing the temperature of the gas. The temperature T (°C) of the wiping gas immediately after being discharged from the tip of the wiping nozzle is controlled so as to satisfy the relationship TM - 150 ≦ T in relation to the melting point TM (°C) of the molten metal M. Here, it is preferable to control the temperature T so as to satisfy TM - 150 ≦ T ≦ TM + 250. Controlling the temperature T within the above range can suppress the cooling and solidification of the molten metal M, making it difficult for viscosity variations to occur and suppressing the occurrence of melt wrinkles. On the other hand, if the temperature T is less than TM - 150 (°C), it does not affect the fluidity of the molten metal M and is therefore ineffective in suppressing the occurrence of melt wrinkles. Furthermore, if the temperature T is higher than TM + 250 (°C), alloying is promoted, deteriorating the appearance of the steel sheet.

[0029] The steel strip S passes through the snout 20 and is continuously introduced into the molten metal M in the coating tank 10. Thereafter, the steel strip S is pulled up from the molten metal M in the coating tank 10 via the sink roll 40 and support roll 50 of the molten metal M.

[0030] Excess molten metal M adhering to the steel strip S is removed by wiping gas injected from a gas injection device 30. The steel strip S is then cooled by cooling equipment (not shown) and is then guided to a subsequent process. In this manner, hot-dip metal coated steel strips are continuously produced. The subsequent process also includes shearing, and steel sheets are produced from the steel strip S.

[0031] In this manner, the wiping gas is sprayed onto both sides of the steel strip S, thereby scraping off excess molten metal M. As a result, the amount of molten metal M deposited on the steel strip S is made uniform in the width and length directions.

[0032] <Gas wiping nozzle> FIG. 2 shows a schematic configuration of the gas wiping nozzle 31. As shown in FIG. 2, the gas wiping nozzle 31 includes a ceramic nozzle portion 33 (ceramic member) that injects wiping gas. The nozzle portion 33 has a supply port 32 through which gas is supplied and an injection port 35 that injects the supplied gas. In this embodiment, the gas wiping nozzle 31 further includes a flange 36 (nozzle header) to which gas is supplied through a pipe, and a rectifying plate 34 connected to the nozzle portion 33. The flange 36 is a member that receives the gas sent to the gas wiping nozzle 31 through the pipe.

[0033] The current plate 34 is formed in a substantially rectangular shape extending in the length direction DX, the depth direction DY, and the width direction DZ. The base end (rear end) of the current plate 34 is connected to a flange 36. As shown in Fig. 2, the metal flange 36 is mechanically connected to a side of the current plate 34 different from the side to which the nozzle portion 33 is connected. Here, the mechanical connection is made by using members such as bolts and screws.

[0034] The nozzle section 33 has a first nozzle member 33a and a second nozzle member 33b arranged opposite each other. In this embodiment, the first nozzle member 33a is arranged on the upper side, and the second nozzle member 33b is arranged on the lower side.

[0035] The first nozzle member 33a and the second nozzle member 33b are provided with a gap between them, so that a slit-shaped injection port 35 is formed between the first nozzle member 33a and the second nozzle member 33b.

[0036] The length direction DX is the direction along the width direction of the steel strip S. The width direction DZ is the direction along the length direction of the steel strip S, i.e., the conveying direction. The width direction DZ is also a direction perpendicular to the length direction DX. The depth direction DY is the direction along the thickness direction of the steel strip S. The depth direction DY is also a direction perpendicular to the length direction DX and the width direction DZ.

[0037] The injection port 35 has a slit-shaped opening that extends in the longitudinal direction DX. The injection port 35 is formed by the first nozzle member 33a and the second nozzle member 33b facing each other in the width direction DZ. That is, the injection port 35 is formed so that the distance between the first nozzle member 33a and the second nozzle member 33b in the width direction DZ is the opening height.

[0038] The injection port 35 is formed so that its length along the longitudinal direction DX is longer than the width of the steel strip S. For example, even if the steel strip S shifts in the longitudinal direction DX when being pulled up from the coating tank 10, the injection port 35 is formed to be sufficiently long, so that the wiping gas can be injected across the entire width of the steel strip S.

[0039] <Nozzle section> As described above, the nozzle section 33 is composed of the first nozzle member 33a and the second nozzle member 33b. Wiping gas is sprayed from the gap between the first nozzle member 33a and the second nozzle member 33b to adjust the film thickness of the molten metal M adhering to the steel strip surface. The first nozzle member 33a and the second nozzle member 33b are formed from a material that is heat resistant to the molten metal M. The material may have a fracture toughness value of, for example, 3 MPa m 1 / 2 The fracture toughness of the material is selected to be greater than or equal to 5 MPa m 1 / 2 It is more preferable that the fracture toughness of the material is 7 MPa m 1 / 2 More preferably, it is equal to or greater than this.

[0040] Furthermore, the material of the first nozzle member 33a and the second nozzle member 33b preferably has low wettability with respect to the molten metal M, low plastic deformability, and a low linear expansion coefficient. Examples of materials that satisfy these conditions include ceramic materials and ceramic-based composite materials (hereinafter referred to as ceramic materials, etc.).

[0041] The ceramic material is not particularly limited, but may be, for example, alumina, sialon, silicon nitride, or zirconia.

[0042] The bending strength of the ceramic material is preferably 600 MPa or more. More preferably, the bending strength of the ceramic material is 800 MPa or more. Examples of ceramic materials that satisfy this condition include zirconia, silicon nitride, and sialon. These ceramic materials are resistant to plastic deformation, and substantial deformation can be suppressed if the strength is below the fracture strength. Furthermore, the Vickers hardness of the ceramic material is preferably 800 HV or more. More preferably, the Vickers hardness of the ceramic material is 1000 HV or more.

[0043] Ceramic materials and the like may crack if their thermal shock resistance is below the temperature of the wiping gas. Therefore, it is preferable that the thermal shock resistance of the ceramic material and the like be equal to or higher than the temperature of the supplied wiping gas. In particular, when high-temperature wiping gas is used, the thermal shock resistance of the ceramic material and the like is preferably 430°C or higher. It is more preferable that the thermal shock resistance of the ceramic material and the like be 600°C or higher.

[0044] Furthermore, the linear expansion coefficients of the first nozzle member 33a and the second nozzle member 33b are preferably not more than half the linear expansion coefficient of the rectifying plate 34. It is more preferable that the linear expansion coefficients of the first nozzle member 33a and the second nozzle member 33b are not more than one-third the linear expansion coefficient of the rectifying plate 34. By satisfying such conditions for the linear expansion coefficients, it is possible to suppress deformation of the first nozzle member 33a and the second nozzle member 33b due to the influence of heat.

[0045] <Heat-resistant materials> In this embodiment, the first nozzle member 33a and the second nozzle member 33b are mechanically connected to the rectifying plate 34. FIG. 3 is a schematic diagram of the AA′ cross section of FIG. 2, showing the interface (metal-ceramic interface) between the rectifying plate 34 (metal) and the first nozzle member 33a (ceramic). FIG. 3 shows a simple bolt fastening (conventional configuration). In a high-temperature environment, the difference in thermal expansion between the metal and ceramics generates thermal stress at the interface, causing damage to the brittle ceramic. When damage occurs to the ceramic, gas leaks from the damaged area, preventing the nozzle from functioning properly. In the gas wiping nozzle 31 according to this embodiment, the nozzle portion 33 and the metal flange 36 are mechanically connected via a heat-resistant material 60. More specifically, as shown in FIG. 4, the nozzle portion 33 (the first nozzle member 33a and the second nozzle member 33b) and the rectifying plate 34 are mechanically connected via the heat-resistant material 60. As described above, the rectifying plate 34 is mechanically connected to the flange 36. With this configuration, even if a difference in thermal expansion occurs, the thermal stress at the interface due to the difference in thermal expansion is alleviated, making it possible to avoid damage to the ceramic. Here, although an example of connection of the first nozzle member 33a is shown in FIGS. 2 to 4, the second nozzle member 33b is also mechanically connected to the rectifying plate 34 (metal). Furthermore, the heat-resistant material 60 may also be inserted between the head portion of the bolt and the nozzle portion 33.

[0046] The heat-resistant material 60 may be a heat-resistant cloth made of, for example, ceramic fiber, glass cloth, ceramic cloth, silica cloth, etc. The ceramic fiber may be, for example, a long fiber containing alumina and silica.

[0047] The heat-resistant material 60 is in the form of a film. The thickness of the film is preferably 0.5 mm or more and 100 mm or less. If the thickness is less than 0.5 mm, the heat-resistant material 60 is too thin and may be damaged when the ceramic and metal are fastened together. If the thickness is more than 100 mm, the heat-resistant material 60 is too thick and may cause looseness when the ceramic and metal are fastened together.

[0048] When fastening ceramics to metal, the tightening torque should be between 2 Nm and 40 Nm. If the torque is less than 2 Nm, the ceramic will fall off the metal during operation. If the torque is more than 40 Nm, the torque will be too strong and the ceramic will be damaged during tightening.

[0049] When chamfering the ceramic slotted hole of the bolt attachment part with a C chamfer, it is preferable that it be C0.5 or more and C10 or less. In other words, it is preferable to cut it at a position 0.5 mm or more and 10 mm or less from the tip of the corner. If it is less than C0.5, the chamfer will be too small and the corner of the ceramic will be damaged. If it exceeds C10, the ceramic slotted hole will be too large, resulting in additional processing costs.

[0050] When chamfering the ceramic slotted hole of the bolt attachment part, it is preferable that R is 0.1 or more and R is 5 or less. In other words, it is preferable to perform circular processing with a radius of 0.1 mm or more and 5 mm or less. If R is less than 0.1, the chamfer is too small and the corners of the ceramic will be damaged. If R exceeds 5, the ceramic slotted hole will be too large, resulting in additional processing costs.

[0051] <Rectifier plate> The gas blown to the flange 36 is subject to considerable turbulence as it passes through the piping, and if it is introduced directly into the nozzle portion 33, the turbulence will cause a bias in the wind speed in the width direction DZ. The rectifying plate 34 is, for example, a metal plate with holes or slits, and the holes or slits serve to narrow the gas flow path. The gas that reaches the rectifying plate 34 passes through the holes or slits provided in the rectifying plate 34 and is discharged uniformly from the outlet of the rectifying plate 34. As a result, wiping gas is discharged uniformly from the outlet of the nozzle portion 33.

[0052] The material of the rectifying plate 34 may be, for example, stainless steel (SUS steel) or chrome molybdenum steel. Similarly, the material of the flange 36 may be stainless steel or chrome molybdenum steel. The linear expansion coefficients of stainless steel and chrome molybdenum steel are approximately 10×10 -6 / K~18×10 -6 / K.

[0053] (Example) A gas injection device 30 was installed in the manufacturing facility 100 for hot-dip metal-plated steel sheets shown in Figure 1, and the presence or absence of damage to the ceramics was measured. More specifically, as shown in Table 1, an evaluation was conducted on a gas wiping nozzle 31 (comparative example) having a conventional configuration and a gas wiping nozzle 31 (example) having the configuration described in the above embodiment. The gas wiping nozzle 31 of the example has a film-like heat-resistant material 60 provided on at least a portion of the surface of the nozzle portion 33 on the side closer to the supply port 32. However, the gas wiping nozzle 31 of the comparative example does not have the heat-resistant material 60 provided thereon.

[0054] Tests were conducted under two temperature conditions for the temperature of the wiping gas. Under the first temperature condition, the gas was pressurized by a compressor located behind the gas wiping nozzle 31, and the temperature of the wiping gas at the nozzle outlet was set to 100°C to 150°C. Under the second temperature condition, high-temperature gas was generated by mixing exhaust gas obtained from the combustor with air, and the temperature of the wiping gas at the nozzle outlet was set to 400°C to 500°C. The temperature of the wiping gas injected from the nozzle portion 33 was measured by a thermocouple attached to the injection port 35. Here, under the second temperature condition, the temperature was adjusted by adjusting the amount of air used to dilute the exhaust gas.

[0055] For each of the comparative examples and examples shown in Table 1, gas was discharged from the nozzle portion 33 continuously for 24 hours, and after the experiment, the nozzle portion 33 was removed and the presence or absence of damage to the ceramic portion was confirmed. The presence or absence of damage was confirmed by fluorescent penetrant testing. The occurrence of cracks was judged to be damage. In other words, the presence or absence of damage was judged as "present (fail)" if even one crack occurred, and "absent (pass)" if no cracks occurred. The experimental results are as shown in Table 1. Here, the materials of the rectifying plate 34 in Table 1, SCM440, SCM435, and SUS310, are based on the classification of SCM steel or SUS steel in the JIS standard.

[0056] In Comparative Examples 1 and 2, in which the heat-resistant material 60 was not inserted at the interface between the metal and the ceramic, cracks (fissures) occurred in the ceramic, and the samples were rejected. In contrast, in Examples 1 to 12, in which ceramic fibers were inserted at the metal-ceramic interface, no damage occurred and the samples were accepted. It is believed that the damage was suppressed by easing the thermal stress generated at the interface.

[0057] [Table 1]

[0058] As described above, the gas wiping nozzle 31, gas injection device 30, and method for manufacturing a hot-dip metal-plated steel sheet according to this embodiment are configured as described above to suppress damage to the ceramic nozzle portion 33. As a result, uneven spray of wiping gas caused by damage to the nozzle portion 33 can be eliminated, reducing plating defects. Furthermore, because the nozzle portion 33 is made of ceramic, adhesion of splashes to the nozzle portion 33 can also be suppressed.

[0059] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or alterations based on the present disclosure, and therefore, it should be noted that these modifications and alterations are included within the scope of the present disclosure. [Explanation of symbols]

[0060] 10 Plating tank 20 Snout 30 Gas Injector 31 Gas wiping nozzle 32 Supply port 33 Nozzle section 33a first nozzle member 33b second nozzle member 34 Rectifier plate 35 Nozzle 36 flange 40 Sink Roll 50 Support Rolls 60 Heat-resistant materials 100 Manufacturing equipment for hot-dip metal coated steel sheets S steel strip M Molten metal

Claims

1. A gas wiping nozzle that sprays gas onto a steel strip pulled up from a molten metal plating bath to adjust the film thickness of molten metal adhering to the surface of the steel strip, a ceramic nozzle portion having a supply port through which the gas is supplied and an ejection port through which the supplied gas is ejected, A gas wiping nozzle, wherein a film-like heat-resistant material is provided on at least a portion of the surface of the nozzle portion on the side closer to the supply port.

2. 2. The gas wiping nozzle according to claim 1, wherein the temperature of the gas sprayed is in the range of 100°C to 150°C.

3. 2. The gas wiping nozzle according to claim 1, wherein the melting point of the molten metal is defined as TM (°C), and the temperature of the sprayed gas is TM-150 (°C) or higher.

4. The gas wiping nozzle according to claim 1 , wherein the nozzle portion and a metal flange are mechanically connected via the heat-resistant material.

5. the nozzle portion and the flow rectifying plate are mechanically connected via the heat-resistant material, The gas wiping nozzle according to claim 4 , wherein the flange is mechanically connected to a side of the straightening plate different from a side to which the nozzle portion is connected.

6. A gas injection device comprising a gas wiping nozzle according to any one of claims 1 to 5.

7. A method for producing a hot-dip metal-plated steel sheet, comprising producing a hot-dip metal-plated steel sheet by using the gas injection device according to claim 6.

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